[Applejinx]

Well that's interesting. They seem to be arguing that the bank angle is super high, causing the planes to pull massive Gs just to land or take off, and that's terrible.

Even if it's true all that means is,

(a) planes achieving takeoff instantly have better than stall speed in the open air and can safely get up and away from the city,

(b) planes landing can come in at any angle, have infinite space to negotiate a decent landing and no specific window to hit as far as retaining enough runway, plus the landing speed is significantly higher than stall speed in free air. That directly improves the controllability of the aircraft.

The guy's right, this would work just fine. Even without a bank and increased G forces, it's not a bad idea, but when you include the reality of the banking increasing takeoff/landing speed over normal stall speed, it becomes a slam dunk. Very good idea anywhere you can afford to build three or more runways in your airport.

[yock]

Regarding a, how do you figure stall speed is higher? Stall-spin accidents occur precisely because aircraft are in a bank near the ground. They're more common on landing than takeoff because procedure often dictates flying the runway heading until having sufficient speed and altitude to recover.

Regarding b, wind direction is still important. Your airspeed would be constantly in flux when negotiating a landing at a bank since your angle to the wind is constantly changing. This is especially perilous at low speed near the ground due to the risk of spinning.

There may absolutely be benefits to a circular runway, but I see a lot of increased risk around inducing low altitude spins.